1) Field of the Invention
Various embodiments of the present invention relate generally to an improved platen assembly for a printer and, more specifically, to a platen assembly that is structured for quick and efficient installation, removal, and/or replacement.
2) Description of Related Art
Platen rollers are widely used in printers to drive media against a printhead during printing operations. The platen roller provides a soft, often rubberized, surface for gripping and manipulating the media against the printhead. For print quality purposes, it is often important for the platen roller to apply a relatively constant and uniform pressure against the printhead along the full length of the platen roller.
Over the lifetime of a printer, platen rollers may need to be replaced due to abuse or normal wear and tear. If not replaced, a worn out or otherwise defective platen roller may provide uneven pressure against the printhead causing poor print quality or other problems. Accordingly, a need exists to ensure that worn or defective platen rollers, and any associated components, may be quickly and efficiently replaced.
For repeatable high quality printing, the printhead is closely aligned with respect to the printer platen. However, each time the platen is exchanged, the alignment between the printhead and platen is disturbed. Thus, a need exists to ensure that a replaced platen may be readily oriented in a fixed and aligned position relative to the printhead.
FIG. 1 depicts a printer structured in accordance with the known prior art. The printer 10 includes a printer housing 14 having a media door 12 that may be opened by a user to expose various internal printer components. In the depicted printer 10, such internal printer components may include a media hanger assembly 13, a platen assembly 20, and a printhead assembly 40. The media hanger assembly 13 may be a hanger as shown for supporting a spooled media such as adhesively backed labels. As is readily apparent to one of ordinary skill in the art, the media is drawn from a media supply spool (not shown) supported by the hanger assembly 13 and fed between the printhead assembly 40 and the platen assembly 20 during printing operations. The printhead assembly 40 may include a thermal demand printhead, an ink jet printhead, or other conventional printhead technologies.
FIG. 2 is a detail view of the prior art platen assembly 20 shown in FIG. 1. The depicted platen assembly 20 includes a platen housing 36 that defines first and second support members 38, 39 that are adapted to support a platen roller assembly 60. The depicted platen roller assembly 60 includes a platen roller 21 and first and second clips 23, 24 for securing the platen roller 21 to the first and second support members 38, 39 at respective ends of the platen roller 21. A drive shaft 22 is provided for connecting to a stepper motor (not shown) that is adapted to drive the platen roller 21 during printing operations.
FIG. 3 is an exploded view of a platen assembly 20 structured in accordance with the known prior art. As noted above, the platen assembly 20 includes a platen roller assembly 60 that is secured to a platen housing 36 by the first and second clips 23, 24. The depicted platen roller assembly 60 includes a platen roller 21, a drive shaft 22, first and second support bearings 33, 34 disposed at opposite ends of the platen roller 21, and a wave spring or washer 35 used in mounting the second support bearing 34 as shown. When the platen roller assembly 60 is installed in the housing 36, the first and second support bearings 33, 34 are positioned within first and second support notches 31, 32 defined in the first and second support members 38, 39 of the housing 36.
In many prior art applications, replacement of the platen roller 21 requires the application of several relatively complex steps. First, the stepping motor (not shown) must be loosened with a screwdriver or similar tool and disengaged from the platen roller assembly 60. A drive belt (not shown) must then be removed from the disengaged stepping motor. Next, as suggested in FIG. 2, two flathead screwdrivers or other similar tools 5 are used to apply pressure to dislocate the barbed first and second clips 23, 24 from the first and second support members 38, 39 of the platen housing 36. Once the clips 23, 24 are removed, the platen roller assembly 60 may be removed from the first and second support members 38, 39 of the platen housing 36.
As will be apparent to one of skill in the art, it is typically quite difficult to manipulate screwdrivers or other tools within the tight confines of the printer housing. It also may be difficult to disassemble the drive assembly (e.g., stepping motor, drive belt, etc.). Thus, it would be desirable then to provide a platen assembly that may be quickly and simply installed and replaced without requiring the use of tools.